If I had to go for an album it would have to be Aurora, by Origa. Difficult to place it in a genre so I will just say Vocal, but she dips into quite a number of genres depending on the album.
However, my favourite obscure song was released as a single only;
Land of Love, also by Origa
Quite possibly the most angelic voice I have ever heard; I have listened to her music at least once a day, every day for the past four years and it has never gotten old.
I guess she may be known to fans of Ghost in the Shell: Stand Alone Complex as she sang the opening tunes to each series, aside from that I do not think she is known at all in the West.